WO2000004409A1

WO2000004409A1 - Refractive index distribution type optical element and refractive index distribution type rod lens array

Info

Publication number: WO2000004409A1
Application number: PCT/JP1999/003748
Authority: WO
Inventors: Jun Yamaguchi; Shuya Kogi
Original assignee: Nippon Sheet Glass Co.,Ltd.
Priority date: 1998-07-16
Filing date: 1999-07-12
Publication date: 2000-01-27
Also published as: CN1274428A; EP1018657A1; CN1135411C; US6141155A; TW405045B; EP1018657A4

Abstract

A refractive index distribution type optical element of a core/clad structure containing metal oxide coloring components in clad glass and being produced by an ion exchange method, wherein the clad glass contains, as the metal oxide coloring components, 0.3 to 4.0 wt.% of CoO, 1.0 to 12.0 wt.% of Fe2O3, 0.0 to 2.0 wt.% of NiO and 0.0 to 0.2 wt.% of Cr2O3 per 100 wt.% of a total of parent glass components excluding the coloring components. Specifically, a core/clad type refractive index distribution type optical element which prevents lowering in optical characteristics to be caused by the presence of portions where a refractive index is outside a parabolic distribution, prevents an intrusion of a flare light and has an excellent resolution even in an optical device using a white light; and a rod lens array using this element.

Description

Description Gradient index optical element and Gradient index lens array

Technical field

The present invention relates to a gradient index optical element and a gradient index rod lens array having a core / cladding structure having a refractive index distribution in a radial direction, and more particularly to an improvement in a cladding glass composition. Background art

A gradient index optical element whose refractive index changes in a parabolic manner from the center to the outer periphery in the cross section, such as a light focusing lens, forms an image similar to a spherical lens even if the lens surface is flat. It is widely used in the optical heads of optical devices such as copiers, optical printers, and facsimile machines because it has an effect and has the advantage of easily producing lenses with a small diameter and single focus. The gradient index optical element includes a gradient index rod lens, a gradient index fiber, and the like.

As a method of manufacturing a refractive index distribution type optical element, an ion exchange method of imparting a refractive index distribution by immersing a glass rod in a molten salt is widely used industrially. For example, a glass port containing cations such as L i +, T 1 + s C s +, and Ag + is immersed in a molten salt such as sodium nitrate / nitrate lime to form a cation in the glass. By exchanging cations in the molten salt, an aperture lens having a refractive index distribution can be obtained.

Instead of using molten salt, the cations in the glass rod and the cations in the glass rod are heated during molding of the core / cladding glass rod coated with the above-mentioned glass rod with a cladding glass layer containing sodium ions and potassium ions or by heating after molding. By exchanging with cations in the glass layer, a core / cladding lens having a refractive index distribution can be obtained. This core / clad glass rod can be manufactured by a double crucible method, a pipe method, or the like.

In the rod lens manufactured by the above-mentioned ion exchange method, ion exchange is mainly performed. As a result, it often deviates from a parabolic distribution (square distribution) mainly in the vicinity of the surface. Fig. 1 shows the refractive index distribution of a core lens with a core / cladding structure. The lens has a circular cross section, a core in the center, and a concentric clad around the core. Below that is the refractive index distribution curve. The horizontal axis r is the radial distance from the center of the core, and n is the refractive index. At this time, the composition of the core glass and the clad glass before the ion exchange should be selected so that the refractive index continuously changes at the boundary between the core and the clad after the ion exchange. This is preferable when the thickness of the cladding layer is to be increased in size.

When trying to transmit information such as images, light rays that pass through the vicinity of the side surface that deviate from this normal parabolic distribution cause distortion and aberration, and reduce the optical characteristics of the refractive index distributed aperture lens. Let it. Also, light (flare light) entering from the outside through the vicinity of the side surface of the gradient index lens also degrades the optical characteristics of the gradient index rod lens.

In order to prevent such a decrease in lens optical characteristics and the invasion of flare light, Japanese Patent Application Laid-Open No. 63-301901 discloses a core / clad glass rod containing a cation such as Li +, for example. For example, a graded index optical element is manufactured by immersing in a molten salt such as sodium nitrate for a predetermined time to exchange lithium ions in the core / cladded glass rod with sodium ions in the molten salt. In this case, glass containing metal ions such as Mn, Cr, Co, Ni, Fe, Cu, Ag, Ti, Pbs Ru, Cd, V, and Mo as coloring components A technique has been disclosed in which a light absorbing layer is formed to prevent flare light from entering. However, the colorant of MnO, CoO, or a combination of Co0 and MnO used in the embodiment is sufficient for an optical device using monochromatic light as a light source, but is not sufficient for an optical device using white light. Had the problem of lack of resolution.

Also, Japanese Patent Application Laid-Open No. 10-139472 discloses that Co〇, MnO, and C as colorants are used as cladding glass layers in a gradient index optical element by a thermal mutual diffusion method using a double crucible. Light absorbing glass containing r2〇3, for example, 1.5% by weight of CoO, 1.0% by weight of MnO, and 0.4% by weight of Cr2〇3 There is disclosed a technique for preventing flare light from entering a manne and improving the accuracy of the outer diameter by using an image. However, this colorant is liable to cause devitrification of the core and the clad glass, and has a problem that the usable glass composition range for the core and the clad glass is narrow and limited. Disclosure of the invention

An object of the present invention is to prevent a decrease in optical characteristics due to a portion where the refractive index deviates from a normal parabolic distribution, prevent flare light from entering, and excel in an optical device using white light. An object of the present invention is to provide a core / cladding type gradient index optical element having high resolution and a rod lens array using the same.

The refractive index distribution type optical element of the present invention is a core / cladding structure refractive index distribution type optical element manufactured by an ion exchange method, wherein the refractive index distribution contains a metal oxide coloring component in the clad glass. In the mold optical element, the clad glass is expressed as a weight percentage of 100% by weight of a total of a mother glass component excluding the coloring component as the metal oxide coloring component,

C ο 0 0 .3〜4.0

F e 2 0 3 1 .0 to 1 2 .0

N i 0 0 .0 to 2.0

C r 2 0 3 0 .0 to 0.2

It is characterized by containing.

The gradient index rod lens array according to the present invention is such that a plurality of such gradient index optical elements according to the present invention are arranged such that their optical axes are parallel to each other and are fixed to each other.

In the present invention, the metal oxide coloring component (hereinafter sometimes referred to as “coloring agent”) in the cladding glass is additional to the mother glass component (base glass component excluding the coloring agent) of the cladding glass. The weight% of the coloring agent is expressed as a percentage by weight of the total amount of the mother glass component of the cloud glass, ie, the weight of the coloring agent when the total of the mother glass component is 100% by weight. Sometimes referred to as “addition amount”). In the gradient index optical element of the present invention, since the coloring agent is added to the clad glass, it is possible to prevent a decrease in optical characteristics due to a portion where the refractive index deviates from the normal parabolic distribution, and to prevent the penetration of flare light. be able to. In particular, by adding a predetermined amount of C ο θ and Fe 2〇 3 as the colorant, and further adding Ni 0 and / or Cr 203 as needed, the wavelength of the entire visible light can be reduced. Since light can be efficiently removed, a core / cladding gradient index optical element having excellent resolution can be obtained even in an optical device using white light. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a refractive index distribution curve of a gradient index rod lens.

FIG. 2 is a side sectional view showing a spinning furnace for producing a double glass rod for a gradient index rod lens of the present invention.

FIG. 3 is a graph showing the transmittance spectral characteristics of the clad glass of Example 1.

FIG. 4 is a graph showing the transmittance spectral characteristics of the clad glass of Example 3.

FIG. 5 is a graph showing transmittance spectral characteristics of the clad glass of Example 4.

FIG. 6 is a graph showing transmittance spectral characteristics of the clad glass of Example 5.

FIG. 7 is a graph showing transmittance spectral characteristics of the clad glass of Example 6.

FIG. 8 is a graph showing the transmittance spectral characteristics of the clad glass of Example 7.

FIG. 9 is a graph showing transmittance spectral characteristics of the clad glass of Example 8.

FIG. 10 is a graph showing the transmittance spectral characteristics of the clad glass of Example 9. FIG. 11 is a graph showing the transmittance spectral characteristics of the clad glass of Example 10; FIG. 12 is a graph showing the transmittance spectral characteristics of the clad glass of Comparative Example 1. FIG. 13 is a graph showing the transmittance spectral characteristics of the clad glass of Comparative Example 3. BEST MODE FOR CARRYING OUT THE INVENTION

First, the metal oxide coloring component (coloring agent) contained in the clad glass according to the present invention will be described.

As the metal oxide used as the colorant for the clad glass, one that is basically unrelated to the ion exchange reaction itself is selected. Generally, in proportion to the increase in the amount of colorant,- JP / 03748 Changes in properties such as density, viscosity and thermal expansion of glass. In addition, when the amount of the coloring agent added is large, devitrification tends to occur during the molding of the core Z-clad glass rod, for example, during the spinning process using a double crucible. Therefore, the amount (% by weight) of the colorant added is preferably as small as possible within a range in which light of a desired wavelength can be absorbed. Furthermore, in order to make the refractive index distribution by the ion exchange method as close as possible to the parabolic distribution, it is preferable that the amount of the coloring agent added is small. From such a viewpoint, C00 is suitable as a coloring agent.

If C0 is contained in the glass, the glass will exhibit an absorption capacity that strongly absorbs light in the 520 to 680 nm band due to C0 + ions. Since the absorption of C 0 increases in proportion to the added amount, the larger the added amount of C 00, the greater the effect of removing light that has entered the cladding layer and does not contribute to imaging. However, for the reasons described above, the amount of Co 2 O added is 0.3 to 4.0% by weight, preferably 0.4 to 2.5% by weight, and more preferably 0.5 to 1% by weight. 5% by weight.

If white light is used as the light source, consideration must be given to the removal of light of the entire visible wavelength. The above-mentioned CoO alone is insufficient in the ability to absorb light having a wavelength of 500 nm or less. Fe ions are used as metal ions that absorb short wavelengths of 500 nm or less. F e ^{3 +} ions strongly absorb light of 380 to 460 nm. F e 203 is an essential component for absorbing visible light of a relatively short wavelength, but if its addition is too large, the glass is liable to devitrify, so it is desirable not to use it excessively. The addition amount is set in the range of 0 to 12.0% by weight according to the composition of the mother glass of the clad glass.

That is, when a glass containing a large amount of MgO is used as the mother glass of the clad glass, devitrification is remarkable, so that the concentration of MgO in the mother glass becomes 100% by weight in total of the mother glass components. when, when expressed in terms of weight percent of more than 5 wt%, the addition amount of F e ₂ 〇 3 1.0 to ^4. is preferably 0 wt%. In particular, when adding N i 0 below as a colorant, the amount of F e 2_Rei 3 is preferably 1. ^{^0-2.} ^Fivefold amount%. When NiO is not added, the amount of 62-3 is desirably 1.5 to 4.0% by weight.

When using a glass with low MgO concentration as the mother glass of the clad glass, Since devitrification hardly occurs, further addition of Fe 2◦3 is possible. Since the absorption of Fe203 is smaller than that of CoO, it is necessary to increase the absorption of Fe203 as much as possible to increase the absorption of light in the wavelength range of 380 to 460 nm and improve the resolution in this wavelength range. desirable. If the MgO concentration in the mother glass is less than 5% by weight, expressed as% by weight, assuming that the total of the mother glass components is 100% by weight, 620;

It can be added up to 2.0% by weight. In particular, when Ni 0 described later is added as a coloring agent, the amount of Fe ₂ 〇3 is preferably 5.0 to 8.0% by weight. When NiO is not added, the amount of Fe2〇3 is desirably 6.0 to 12.0% by weight.

According to the present invention, in particular, by coexisting Co 2 + ions and Fe ³ + ions in the clad glass, it is possible to efficiently remove light having a wavelength of the entire visible light.

Ni0 is not an essential component, but when used together with Co0 and Fe203, the light in the band between the visible light absorption region by Co0 and the visible light absorption region by Fe203 (420 to (500 nm). If the amount of NiO added is too large, the glass tends to be devitrified, so it is desirable that the amount of NiO be as small as possible. The addition amount of NiO is 0.0 to 2.0% by weight, preferably 0.2 to 2.0% by weight, and more preferably 0.2 to 1.0% by weight.

Other metal ions that absorb short wavelengths in the visible light region include Cr, Μη, and the like. Mil or Cr can be added to the above-mentioned Co, Fe, and Ni in addition as described below.

Although Cr 203 is not an essential component, it strongly absorbs light of 380 to 430 nm similarly to Fe 203, and its absorption ability is higher than that of Fe 203. However, Cr2-3 tends to devitrify clad glass, especially glass containing lithium. If the added amount of Cr2〇3 is 0.2% by weight or less, it can be added without devitrifying the glass.

MnO is not an essential component, but when it exists in the form of Mn ³ + ions in glass, it strongly absorbs light of 440 to 500 nm. However, in a state MnO is coexisting with F e ₂ 〇 3, in the form of Mn ² + ions, since the light is no longer absorbs almost, but not safely be added 1.0 wt% or less, effective as a colorant is not.

Components of mother glass before ion-exchange treatment of cloud glass containing the above colorants Preferable examples of the composition are as follows in terms of% by weight (however, the total is 100% by weight).

[Composition of mother glass of clad glass (before ion exchange treatment) (% by weight)]

J 丄 re n

Na 0 1 ~ 2 8

M O 2.5-1

B a 0 2〜10

PbO 0-25

T i 0 ₂ 2 to 10

S i 0 ₂ 45 -60

A preferred example of the component composition of the core glass before the ion exchange treatment is as follows in terms of% by weight (however, the total is 100% by weight).

[Core glass composition (before ion exchange treatment) (% by weight)]

L i ₂₀ 3 to 12

N a 20 0-15

MgO 2.5-15

B a 0 2〜10

PbO 0-25

T i 0 ₂ 2 to 10

S i 0 ₂ 45 ~ 60

Note that the composition of both the clad glass and the core glass is not uniform but distributed radially (particularly, Li 20 and Na 20 components) as a result of the ion exchange treatment. The component compositions of the mother glass and the core glass of the clad glass of the refractive index distribution type optical element of the present invention manufactured as described above are expressed in terms of% by weight on average and are as follows (provided that the total is 10%). 0 wt%), the Na20 content in the clad glass is larger than the Na20 content in the core glass, and the Li20 content in the core glass is Li0 in the clad glass. It is preferable that the content is larger than the content. Here, “average” means that the following composition distributions are homogenized in the clad glass and core glass, respectively. It means that it is a calculated value.

[Average mother glass composition of clad glass (after ion exchange treatment) (% by weight)]

L i 0 0.5 to 1 2

N a 0 14-28

M g 0 2.5 to 15

2 to 1 0

Pb 00-25

T i 0 2-10

S i 0? 45-60

A glass day 5 ^ f ion Ι®

L i 90 2 to 9

n ~

I a 2 ^

MgO 2.5 to 15

B aO 2 ~: I 0

PbO 0-25

T i0 ₂ 2 to 10

S i0 ₂ 45〜 60

The refractive index distribution type optical element of the present invention produces a core / cloud glass rod according to an ordinary method using a glass base material having a predetermined composition obtained by adding a coloring agent to a mother glass and a core glass base material. For example, the glass rod can be manufactured by immersing the glass rod in a molten salt such as sodium nitrate for a predetermined period of time to exchange ions between lithium ions in the core / cloud glass rod and sodium ions in the molten salt.

The thus-produced gradient index optical element of the present invention preferably has a core glass having a diameter of 100 to 1000 m and a cladding glass layer having a thickness of 1 to 100 m (provided that the thickness of the cladding glass layer is sufficient). Is preferably 1 to 25% of the core glass diameter), has a refractive index constant (g) of 0.1 to 4, and the glass of the clad glass layer has a thickness of 380 nm when the thickness is 100 m. It has a transmittance of less than 75% for light of all wavelengths in the range of 680 nm. 7 Further, the gradient index rod lens array of the present invention includes 50 to 100 refractive index gradient optical elements of the present invention, such that their optical axes are parallel to each other, and The optical elements are manufactured by arranging them in one or two to four rows in a staggered manner so that both end faces of the optical elements form the same plane, and fixing them together using an adhesive. Example

Hereinafter, the present invention will be described more specifically with reference to practical examples and comparative examples. However, the present invention is not limited by the following embodiments without departing from the gist thereof. Implementation 咧 1, Comparative Examples 1-4

A hollow cylindrical clad glass having the composition shown in Tables 1 and 3 and having a thickness of 0.5 mm and an inner diameter of 30.5 mm, and a core glass head with a diameter of 30 mm inserted therein were used. By heating in an electric furnace at 65 ° C. and stretching with a tension roller, the hollow cylindrical clad glass and the core glass rod are fused and integrated, and each core has an outer diameter of 300 m. A core / clad glass rod with a diameter of 295 jam (cladding layer thickness of 2.5 rn) was obtained. In addition, in the glass compositions of Tables 1 and 3 and Table 2 described below, the added amount (% by weight) of the colorant is a value in which the total of the mother glass components other than the colorant is 100% by weight.

This glass rod was cut into a length of about 1 m, immersed in a bath of molten sodium nitrate maintained at about 445 ° C for about 24 hours, and the lithium ions in the glass rod were removed. After the ion exchange with the sodium ion in the molten salt, it was pulled up. This rod was cut, and both end faces were polished flat to obtain a rod lens having a length of 4.13 mm or 4.01 mm and a refractive index distribution. Table 4 shows the outer diameter, length, refractive index (n ₀ ) on the central axis, refractive index constant (g :), and TC (distance between object images at which a 1 × real erect image is formed) of this rod lens. As shown in FIG. In addition, the refractive index constant (g) is defined as the distribution of the refractive index (n) in the radius (r) direction, where n ₀ is the refractive index on the central axis.

n = n 0 (1-g r ^)

Is a constant when approximated by And the refractive index was continuously changing at the boundary between the core and the cladding.

In addition, about 200 refractive index distribution type rod lenses are set so that their optical axes are parallel to each other. Then, the lenses were arranged in two rows in a zigzag pattern and fixed to each other using an adhesive to produce a lens array. For this load lens array, the spatial frequency of the grid pattern was 12 Lp / mm, and the value of the MTF (Modulation Transfer Function) at 470, 530, and 660 nm wavelengths was measured using white light as the measurement light. Was measured, and the results are shown in Table 4. The MTF is the ratio of the contrast between the object and the image as a function of the spatial frequency.The closer the MTF is to 100%, the more faithful the original image is formed, and the higher the resolving power is maintained. Indicates that

In Comparative Example 2 using CoO, {η}, and Cr 203 as the coloring agent, the devitrification often occurred in the clad glass during heating and stretching in a heating furnace, and the resulting double glass The optical characteristics of the aperture lens array could not be measured because the diameter of the lens was not uniform.

Example 2: L 0

A double glass rod was obtained as follows by spinning using a double crucible shown in Fig. 2 using the compositions shown in Tables 1 and 2 for the core and clad glass. In FIG. 2, the double crucible 1 is composed of an inner crucible 2 and an outer crucible 3, and the inner glass 2 and the outer glass 3 are charged with glass cullets for core glass and glass, respectively. Then, the core glass 4 is drawn out from the inner crucible 2 and the clad glass 5 containing the coloring agent is drawn out from the lower nozzle 6 from the inner crucible 3 and spun by a pulling roller (not shown) to fuse them together. -Core / Clad glass rod can be obtained by embodying. Each glass rod was subjected to an ion exchange treatment in exactly the same manner as in Example 1 to produce a rod lens and an aperture lens array having a refractive index distribution, and the optical characteristics are shown in Table 4.

The transmittance spectrum of the clad glass used in Example 1 (C 001.0% by weight, Fe 2〇33.0% by weight) among the above-mentioned examples and the comparatively used clad glass used in the comparative example. The properties (converted to glass thickness of 0.1 mm) are shown in Fig. 3, and the clad glass used in Example 3 (CoO 1.0 wt%, Fe203 2.0 wt%, Ni00.5 wt%) Fig. 4 shows the transmittance spectral characteristics (converted to a glass thickness of 0.1 mm) of the clad glass used in Example 4 (CoO 1.0% by weight, Fe 203 10.0 weights). Fig. 5 shows the transmittance spectral characteristics (converted to glass thickness of 0.1 mm) of the clad glass (CoO 1.0 wt%, Fe 203 6.0 wt%, N Figure 6 shows the transmittance spectral characteristics (converted to glass thickness 0.1 mm) of i 0 1.0 wt%), and the clad glass (CoC2.0 wt%, Fe 203 6. FIG. 7 shows the transmittance spectral characteristics (converted to a glass thickness of 0.1 mm) of the clad glass (3.5% by weight of CoO, 3.0% by weight of Fe203) used in Example 7. Fig. 8 shows the transmittance spectral characteristics (converted to a glass thickness of 0.1 mm), and the transmittance spectral characteristics of the clad glass (3.5% by weight of CoO, Fe 203 10.0% by weight) used in Example 8. Figure 9 shows the glass thickness (converted to 0.1 mm thickness) of the clad glass used in Example 9 (1.0% by weight of CoO, 1.03% by weight of Fe203, and 3.75% by weight of Ni). Fig. 10 shows transmittance spectral characteristics (converted to glass thickness of 0.1mm). The transmittance spectral characteristics (glass thickness 0.1 mm conversion) of the clad glass (1.0% by weight of CoO, 10.0% by weight of Fe203, 1.75% by weight of NiO) used in Example 10 were measured. Fig. 11 shows the transmittance spectral characteristics (converted to a glass thickness of 0.1 mm) of the clad glass (CoO 1.0% by weight) used in Comparative Example 1, and Fig. 12 shows the transmittance of the clad glass (CoO thickness: 0.1 mm) used in Comparative Example 3. Fig. 13 shows the transmittance spectral characteristics (converted to glass thickness of 0.1mm) for 1.0% by weight of CoO and 0.5% by weight of NiO.

/ JP9 8 Table 1

Example 1 Example 2 Example 3 Example 4 Example 5

11a Crack core clad,:] a clad,] a clad core crack

Li ₂ 0 4.2 0.0 5.5 0.0 4.2 0.0 4.2 0.0 4.2 0.0 Mother

Gas Na ₂ 0 8.3 16.4 7.6 17.9 8.3 16.4 8.3 16.6 8.3 16.6

gO 8.4 8.1 8.0 7.6 8.4 8.1 1 8.4 4.5 8.4 4.5

PbO 20.0 19.1 19.2 18.1 20.0 19.1 20.0 19.1 20.0 19.1 ri BaO 4.6 4.4 5.0 4.7 4.6 4.4 4.6 4.3 4.6 4.3

0 /

Ti0 ₂ 4.2 4.0 6.2 5.9 4.2 4.0 4.2 3.7 4.2 3.7

Si0 ₂ 50.3 48.0 48.5 45.8 50.3 48.0 50.3 51.8 50.3 51.8

CoO 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 Color

Agent Fe ₂ 0 ₃ 0 3.0 0 3.0 0 2.0 0 10. 0 0 6.0

NiO 0 0 0 0 0 0.5 0 0 0 1.0 village MnO 0 0 0 0 0 0 0 0 0 0 0 /

/ 0

Cr ₂ 0 ₃ 0 0 0 0 0 0 0 0 0 0

Example 6 Example 7 Example 8 Example 9 Example 10 0 core clad 17 clats, core clad core clad core clad

Li ₂ 0 4.2 0.0 4.2 0.0 4.2 0.0 4.2 0.0 4.2 0.6 Mother

Moth Na ₂ 0 8.3 16.6 8.3 16.6 8.3 16.6 8.3 16.6 8.3 16.6

MgO 8.4 4.5 8.4 4.5 8.4 4.5 8.4 4.5 8.4 4.5

PbO 20.0 19.1 20.0 19.1 20.0 19.1 20.0 19.1 20.0 19.1 ri BaO 4.6 4.3 4.6 4.3 4.6 4.3 4.6 4.3 4.6 4.3

% Ti0 ₂ 4.2 3.7 4.2 3.7 4.2 3.7 4.2 3.7 4.2 3.7

Si0 ₂ 50.3 51.8 50.3 51.8 50.3 51.8 50.3 51.8 50.3 51.8

CoO 0 2.0 0 3.5 0 3.5 0 1.0 0 1.0 color

Agent Fe ₂ 0 ₃ 0 6.0 0 3.0 0 10. 0 0 3.0 0 10.0

NiO 0 0 0 0 0 0 0 1.75 0 1.75 ri MnO 0 0 0 0 0 0 0 0 0 0

0 /

/ 0

Cr ₂ 0 ₃ 0 0 0 0 0 0 0 0 0 0 Table 3

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Core Cladding, SORT, Core Cladding, Core Cladding, Core Cladding

Li ₂ 0 4.2 0.0 4.2 0.0 4.2 0.0 4.2 0.0 Mother

Gas Na ₂ 0 8.3 16.4 8.3 16.4 8.3 16.4 8.3 16.4 G MgO 8.4 8.1 8.4 8. 1 8.4 8. 1 8.4 8.1

PbO 20.0 19.1 20.0 19.1 20.0 19.1 20.0 19.1 ri BaO 4.6 4.4 4.6 4.4 4.6 4.4 4.6 4.4

0 /

/ 0 Ti0 ₂ 4.2 4.0 4.2 4.0 4.2 4.0 4.2 4.0

Si0 ₂ 50.3 48.0 50.3 48.0 50.3 48.0 50.3 48.0

CoO 0 1.0 0 1.0 0 1.0 0 1.0 Color

Agent Fe ₂ 0 ₃ 0 0 0 0 0 0 0 0

NiO 0 0 0 0 0 0.5 0 0 village MnO 0 0 0 0.75 0 0 0 1.5

0 /

/ 0

Cr ₂ 0 ₃ 0 0 0 0.25 0 0 0 0

oi i / oo O0 / 66u7: M £ <1> dl one inch z.

O'ZZ V \ L 9'Si, 8'9i 'LL I'll I'LL L' L 6'S Γ9 S * i 9 "9i rauo99 'Z 8" C O'Si Γ9Ζ 0 "A I'll' ll 9'9 Ή CZ 'U 6 8'CZ muo s

Z'9 Q 'S * IS 9'9Z C * 9' ZL VZL 'L 0 * 9Z Z'ZL d'lL 8- O ^

OZ'Q 02'6 OZ'6 OZ'6 0Z * 6 QZ'Q 0Z * 6 02.6 0Z "6 OZ'6 T8 OZ'6 (ran) 01

T68 * 0 T68 * 0 T68 "0 Ϊ68Ό Ϊ68Ό Τ68Ό Ϊ68Ό Ϊ68Ό Ϊ68.0 168 * 0 168 * 0 0C6 * 0 Ϊ68Ό

ZW \ Ζ19Ί zw \ Ζΐ9ϊ 1W \ Zld'l ZW \ ZW \ ZW \ ZW \ 0S9'T ZW \

ZV εΐ · εΐ · Z \ 'f cr CT' TO '\' (picture)

OC'O οε · ο OC'O OC "0 οε · ο οε · ο OC'O οε · ο οε · ο οε · ο OC'O OC'O OC'O (ΠΜ) c ΐ Οΐ 6 8 I 9 S ε Z ΐ m

Comparison with Examples 1 to 10 ίComparing with Rows 1, 3, and 4, the results are as follows.Each of the samples 1 to 10 shows that at each wavelength of 470, 530, and 660 nm, High MTF values have been obtained. On the other hand, in Comparative Examples 1, 3 and 4, the MTF value at 470 nm was low, indicating that the resolution was reduced when a white light source was used. In Examples 1 and 2, although the coloring components were the same and the mother glass compositions of the core and the clad glass were different, devitrification did not occur. On the other hand, in Comparative Example 2, although core and clad glass having the same mother glass composition as in Example 1 were used, devitrification occurred. Industrial applicability

As described above, according to the present invention, the core / clad double glass rod containing at least the coloring components of Co and Fe in the clad glass is ion-exchanged, so that the outer diameter accuracy is extremely high. Well, it reduces the influence of light passing through the part where the refractive index distribution is disturbed in the outer peripheral part, prevents invasion of flare light, and has a high refractive index distribution rod with excellent resolution even in optical devices using white light. A lens and a lens array can be obtained.

Claims

The scope of the claims

1. A gradient index optical element having a core / cladding structure manufactured by an ion exchange method, wherein the cladding glass contains a metal oxide coloring component.

The clad glass is expressed as a metal oxide coloring component in terms of% by weight, with the total of the mother glass components excluding the coloring component being 100% by weight.

C o 0 0.3 to 4.0

F e 203 1.0-12.0

N i 0 0.0 to 2.0

C r 03 0.0-0.2

And a gradient index optical element comprising:

2. The above-mentioned clad glass is expressed in terms of% by weight, with the total of the mother glass components excluding the coloring component being 100% by weight as the metal oxide coloring component,

C o 0 0.5-: L. 5

F e 003 1.5 to 4.0

N i〇 0

2. The gradient index optical element according to claim 1, comprising:

3. The above-mentioned clad glass is expressed in terms of% by weight, with the total of the mother glass components excluding the coloring component being 100% by weight as the metal oxide coloring component,

C o 0 0.5 to 1.5

F e 203 1.0-2.5

N i 0 0.2 to 2.0

2. The gradient index optical element according to claim 1, comprising:

4. The refractive index distribution type light according to claim 2 or 3, wherein the mother glass contains 5% by weight or more of Mg0 in terms of% by weight, where the total of the mother glass components is 100% by weight. Element.

5. The above-mentioned clad glass is expressed as% by weight, with the total of the mother glass components excluding the coloring component as 100% by weight as the metal oxide coloring component, C o 0 0.5-: L. 5

F e 203 6.0-12.0

N i 0 0

2. The gradient-index optical element according to claim 1, comprising:

6. The above-mentioned clad glass is expressed as% by weight, with the total of the mother glass components excluding the coloring component as 100% by weight as the metal oxide coloring component,

C 00 0.5 to 1.5

F e 20 -5 5.0 to 8.0

N i 0 0.2 to 2.0

2. The gradient index optical element according to claim 1, comprising:

7. The gradient index light according to claim 5 or 6, wherein the mother glass contains less than 5% by weight of Mg0, expressed as% by weight, with the total of the mother glass components being 100% by weight. Element.

8. The clad glass is expressed as a mother glass component, expressed as a percentage by weight on average, as L i 20 0.5 to 12

Na 20 14-28

However, the sum of L i 20 and N a 20 15 to 29

MgO 2.5-; L 5

B aO 2 ~: L 0

PbO 0-25

T i 0 ₂ 2-10

S i O 2 45-60

Containing

The glass that constitutes the core is, on average, expressed in weight percent,

L i 20 2 to 9

N a 20 0.5 to 25

However, the sum of Li 20 and Na 20 is 4 to 29

M O 2.5 to 15

B a 0 2 ~ 10 P b 0 0 ~ 2 5

T i 02 2-; L 0

S i 02 4 δ ~ β 0

And the Na 20 content in the clad glass is higher than the Na 20 content in the core glass, and the Li 20 content in the core glass is higher than the Li 2◦ content in the clad glass. Item 8. The gradient index optical element according to any one of Items 1 to 7.

9. The cladding glass layer has a thickness of 1 to 100 μm, and when the cladding glass has a thickness of Ι Ο ΛΖΠΙ, all the layers in the range of 380 nm to 680 nm are provided. 9. The gradient index optical element according to claim 1, having a transmittance of not more than 5% for light having a wavelength of:

10. The method according to claim 1, wherein the diameter of the core glass is 100 to 100Οχππ, and the thickness of the cladding glass layer is 1 to 25% of the diameter of the core glass. 2. The gradient index optical element according to item 1.

1 1. A plurality of the gradient index optical elements according to any one of claims 1 to 10, which are arranged so that their optical axes are parallel to each other and are fixed to each other.